Only load ~/.cargo/config for cargo install

This commit tweaks how configuration is loaded for `cargo install`, ensuring
that we only load configuration from `$HOME` instead of the current working
directory. This should make installations a little more consistent in that they
probably shouldn't cover project-local configuration but should respect global
configuration!

Closes #6025

Author: alexcrichton

Cargo.toml

@@ -36,7 +36,7 @@ home = "0.3"
 ignore = "0.4"
 lazy_static = "1.0.0"
 jobserver = "0.1.11"
-lazycell = "1.0"
+lazycell = "1.2.0"
 libc = "0.2"
 log = "0.4"
 libgit2-sys = "0.7.5"

src/bin/cargo/commands/install.rs

@@ -74,12 +74,9 @@ continuous integration systems.",
 }
 
 pub fn exec(config: &mut Config, args: &ArgMatches) -> CliResult {
+    config.reload_rooted_at_cargo_home()?;
     let mut compile_opts = args.compile_options(config, CompileMode::Build)?;
 
-    // for `cargo-install` we want to use what the user specified via `--target` and ignore what's
-    // in `.cargo/config` and what the environment says
-    compile_opts.build_config.requested_target = args.target();
-
     compile_opts.build_config.release = !args.is_present("debug");
 
     let krates = args.values_of("crate")

src/cargo/util/config.rs

@@ -281,6 +281,13 @@ impl Config {
         }
     }
 
+    pub fn reload_rooted_at_cargo_home(&mut self) -> CargoResult<()> {
+        let home = self.home_path.clone().into_path_unlocked();
+        let values = self.load_values_from(&home)?;
+        self.values.replace(values);
+        Ok(())
+    }
+
     pub fn cwd(&self) -> &Path {
         &self.cwd
     }
@@ -611,9 +618,16 @@ impl Config {
 
     /// Loads configuration from the filesystem
     pub fn load_values(&self) -> CargoResult<HashMap<String, ConfigValue>> {
+        self.load_values_from(&self.cwd)
+    }
+
+    fn load_values_from(&self, path: &Path)
+        -> CargoResult<HashMap<String, ConfigValue>>
+    {
         let mut cfg = CV::Table(HashMap::new(), PathBuf::from("."));
+        let home = self.home_path.clone().into_path_unlocked();
 
-        walk_tree(&self.cwd, |path| {
+        walk_tree(path, &home, |path| {
             let mut contents = String::new();
             let mut file = File::open(&path)?;
             file.read_to_string(&mut contents)
@@ -1535,7 +1549,7 @@ pub fn homedir(cwd: &Path) -> Option<PathBuf> {
     ::home::cargo_home_with_cwd(cwd).ok()
 }
 
-fn walk_tree<F>(pwd: &Path, mut walk: F) -> CargoResult<()>
+fn walk_tree<F>(pwd: &Path, home: &Path, mut walk: F) -> CargoResult<()>
 where
     F: FnMut(&Path) -> CargoResult<()>,
 {
@@ -1552,12 +1566,6 @@ where
     // Once we're done, also be sure to walk the home directory even if it's not
     // in our history to be sure we pick up that standard location for
     // information.
-    let home = homedir(pwd).ok_or_else(|| {
-        format_err!(
-            "Cargo couldn't find your home directory. \
-             This probably means that $HOME was not set."
-        )
-    })?;
     let config = home.join("config");
     if !stash.contains(&config) && fs::metadata(&config).is_ok() {
         walk(&config)?;

tests/testsuite/install.rs

@@ -1256,20 +1256,39 @@ warning: be sure to add `[..]` to your PATH to be able to run the installed bina
 }
 
 #[test]
-fn install_ignores_cargo_config() {
+fn install_ignores_local_cargo_config() {
     pkg("bar", "0.0.1");
 
     let p = project()
         .file(
             ".cargo/config",
             r#"
-            [build]
-            target = "non-existing-target"
-        "#,
+                [build]
+                target = "non-existing-target"
+            "#,
         )
         .file("src/main.rs", "fn main() {}")
         .build();
 
     p.cargo("install bar").run();
     assert_has_installed_exe(cargo_home(), "bar");
 }
+
+#[test]
+fn install_global_cargo_config() {
+    pkg("bar", "0.0.1");
+
+    let config = cargo_home().join("config");
+    let mut toml = fs::read_to_string(&config).unwrap_or(String::new());
+
+    toml.push_str(r#"
+        [build]
+        target = 'nonexistent'
+    "#);
+    fs::write(&config, toml).unwrap();
+
+    cargo_process("install bar")
+        .with_status(101)
+        .with_stderr_contains("[..]--target nonexistent[..]")
+        .run();
+}